CRM Glossary

RFM segmentation

A customer-segmentation framework that scores each customer on Recency, Frequency, and Monetary value — three ordinal dimensions that together classify the customer base into behavioural bands.

LTV (Customer Lifetime Value)

The total contribution a customer produces across their relationship with the business, typically computed as (ARPU × gross margin) ÷ monthly churn rate for subscription models.

CAC (Customer Acquisition Cost)

The fully-loaded cost of acquiring a paying customer — paid media, creative production, tooling, and attributable headcount divided by customers won in the same window.

Payback period

The number of months of customer contribution it takes to recover the CAC — computed as CAC ÷ (ARPU × gross margin).

Churn rate

The percentage of customers who cancel, lapse, or become inactive in a fixed time window — usually computed monthly for subscription businesses, per-cohort for one-time purchase businesses.

Cohort analysis

Grouping customers by a shared start event (sign-up month, first purchase) and tracking their behaviour over time to expose retention, churn, and LTV dynamics aggregate metrics hide.

Lifecycle stage

A label describing where a customer sits in the buying / using / churning arc — new, active, at-risk, dormant, reactivated — which drives which lifecycle program they're eligible for.

Activation

The event that marks a new user reaching "first value" — the behaviour that predicts they'll stick around, used as the exit-criterion for onboarding programs and the primary KPI for lifecycle teams working top-of-funnel.

North star metric

The single metric that best captures a product's delivered value — chosen because moving it should move revenue, retention, and growth together.

Net revenue retention

The percentage of recurring revenue retained from existing customers over a period, including expansion (upgrades) and net of churn (cancellations, downgrades) — above 100% means the existing customer base is growing revenue without new acquisition.

Gross revenue retention

The percentage of recurring revenue retained from existing customers, excluding expansion — measures pure churn and downgrade without being masked by upsell. Paired with NRR, the gap reveals expansion health.

Product-qualified lead (PQL)

A user who has demonstrated product-usage patterns that predict willingness to convert to paid — the product-led-growth equivalent of a marketing-qualified lead, computed from behavioural signals rather than firmographic intent.

Cohort retention curve

A chart plotting the percentage of a cohort still active at each week or month after their start event — reveals the shape of retention decay: steep early drop-off, settling plateau, long-tail decline.

IP warming

Gradually ramping email volume from a new or dedicated IP over 2-6 weeks to build sender reputation — mailbox providers watch early volume and engagement signals to decide whether the IP is legitimate.

Sender reputation

A per-IP and per-domain score mailbox providers use to decide whether to inbox, tab, or junk a sender's mail — driven mostly by complaint rate, bounce rate, engagement, and authentication alignment.

SPF (Sender Policy Framework)

A DNS TXT record that declares which IPs are authorised to send mail on behalf of a domain — one of the three email-authentication signals (SPF, DKIM, DMARC) mailbox providers check on every message.

DKIM (DomainKeys Identified Mail)

A cryptographic signing mechanism where sending servers sign each message with a private key, and receiving servers verify the signature against a public key published in DNS — proves the message wasn't altered in transit and came from an authorised sender.

DMARC

A DNS policy record that ties together SPF and DKIM results, declares what receivers should do with mail that fails both (monitor, quarantine, reject), and sends aggregate reports back to the domain owner.

BIMI (Brand Indicators for Message Identification)

An email-authentication extension that lets a brand display its verified logo next to messages in the inbox — requires DMARC at enforcement, a VMC (Verified Mark Certificate), and an SVG logo published in DNS.

Gmail promotions tab

Gmail's automatic tabbing system that moves promotional marketing email into a separate Promotions tab rather than the main Primary inbox — algorithm-driven, no declared rule, mostly based on sender reputation and message content signals.

Apple Mail Privacy Protection (MPP)

An iOS 15+ and macOS 12+ feature that pre-fetches tracking pixels and masks recipient IP addresses for users who opt in — inflates apparent open rates to near 100% and breaks open-based engagement metrics for Apple Mail clients, which represent 50%+ of email users.

Gmail 102 KB clipping

Gmail's behaviour of truncating email HTML at 102 kilobytes — anything beyond that is hidden behind a "View entire message" link, cutting off unsubscribe footers, tracking pixels, and any content below the threshold.

Dedicated IP

A sending IP address used by exactly one brand — the brand's send volume, engagement, and complaint rate entirely determine its reputation. Requires warm-up and typically only worth it at 100K+ sends per month.

Shared IP

A sending IP used by many brands through an ESP — the pooled reputation averages engagement signals across all senders on the IP. No warm-up required, but individual brand reputation can be damaged by co-tenants' mistakes.

Suppression list

The list of email addresses that must never be sent to — unsubscribes, hard bounces, spam complaints, and known-invalid addresses. Required by law in most jurisdictions; required by deliverability discipline everywhere else.

Spam trap

An email address mailbox providers and deliverability services create specifically to catch senders with poor list hygiene — sending to one damages reputation immediately, sending to many can get a domain blacklisted.

Google Postmaster Tools

Gmail's free dashboard exposing per-domain reputation, spam-rate, authentication pass rates, delivery errors, and IPv6 reputation — the only direct window into how Gmail currently scores your sending.

Inbox placement

The percentage of sent messages that landed in the Primary inbox vs Promotions tabs, spam folder, or were blocked entirely — measured via seed tests across real accounts at major mailbox providers.

Seed list

A panel of real test-email accounts across the major mailbox providers used to verify where a send actually lands — Primary inbox, Promotions, spam, or blocked. The only reliable way to measure inbox placement.

List-Unsubscribe header

An SMTP header that lets mailbox providers render a native one-click unsubscribe button — required for bulk senders by Gmail and Yahoo since 2024.

Hard bounce

A delivery failure the mailbox provider signals as permanent — invalid address, domain doesn't exist, mailbox closed. The address must be immediately suppressed; future sends damage sender reputation.

Soft bounce

A delivery failure the mailbox provider signals as temporary — full mailbox, server down, message too large, temporary rate-limit. Retry is appropriate; continued soft bounces eventually convert to hard-bounce suppression.

Complaint rate

The percentage of sent messages that a recipient marks as spam — the single most damaging deliverability signal. Gmail specifically enforces a 0.3% threshold; above that, delivery is systematically degraded for weeks.

Welcome series

A sequence of automated emails (typically 3-7) triggered by sign-up that onboards a new subscriber or customer — the single highest-ROI lifecycle program for most businesses because the audience is at peak intent.

Win-back campaign

A lifecycle program targeting customers who have gone dormant — lapsed a defined inactivity threshold — with the goal of re-engaging them before formal churn via incentive, content, or explicit preference check.

Transactional email

An email triggered by a specific user action or system event — order confirmation, password reset, receipt, shipping update — distinguished from promotional email by its primarily informational purpose and the recipient's direct expectation of receiving it.

Browse abandonment

A triggered email program for logged-in users who viewed specific products but didn't add to cart — one of the highest-ROI lifecycle programs for e-commerce, pairing intent signal with personalised product content.

Double opt-in

A sign-up pattern requiring users to confirm their email address by clicking a link in a verification email before being added to the active marketing list — substantially improves list quality and reduces spam-trap risk.

Cart abandonment

A triggered email program for users who added items to cart but didn't complete checkout — the highest-ROI email program most e-commerce brands run, with 10-30% recovery rates typical for well-built flows.

Post-purchase flow

A triggered email sequence after a completed purchase — order confirmation, shipping updates, delivery confirmation, usage / how-to-use content, review request, and cross-sell — designed to drive repeat purchase and reduce returns.

Preference center

A user-facing page where subscribers can choose which types of email they receive, how frequently, and on what topics — reduces unsubscribe rate vs all-or-nothing by letting users throttle instead of leaving entirely.

Sunset flow

A final sequence of 2-3 emails sent to subscribers who haven't engaged for 9-12 months — gives them a final chance to re-engage before being suppressed from the active list. Protects sender reputation from dead weight.

Liquid (Braze templating)

A templating language used in Braze, Shopify, and Jekyll for inserting dynamic variables, conditionals, loops, and filters into email, push, and in-app content — enables personalisation without code-level integration.

Canvas (Braze)

Braze's visual journey builder — a node-based flow diagram where each node is a message, delay, conditional split, or experiment branch, used to build multi-step lifecycle programs without code.

Content Block (Braze)

A reusable HTML fragment in Braze that can be inserted into multiple email templates — change it once, every template that references it updates automatically.

Custom attribute

A user-level data field — beyond the built-in properties like email and first_name — that stores brand-specific information (subscription tier, last-purchase date, NPS score) for use in segmentation and personalisation.

Preheader

The snippet of text shown next to the subject line in the inbox preview — typically 40-130 characters visible depending on client, often pulled from the email's first line of text if not set explicitly.

Plain-text alternative

The plain-text version of an HTML email that sits alongside the HTML in the message's MIME structure — fallback for clients that don't render HTML, accessibility signal for mailbox providers, and a deliverability micro-signal.

Dark mode email

The practice of designing email templates to render correctly when the recipient's client is in dark mode — inverted colour palettes, logo variants that don't disappear on dark backgrounds, and colour-scheme-aware CSS.

Sender name

The human-readable name that appears in the inbox as the sender — paired with the From email address. Often the most influential single factor in open rate: recognisable sender names open consistently, generic or unrecognised names get ignored.

A/B testing

A randomised experiment where two (or more) variants are shown to different user groups and compared on a primary metric — requires sufficient sample size, a pre-declared hypothesis, and statistical significance testing before declaring a winner.

Statistical significance

The probability that an observed difference between two A/B test variants could have occurred by chance — conventionally, a result is 'significant' when the p-value is below 0.05 (95% confidence the difference is real).

Minimum detectable effect (MDE)

The smallest lift the test is powered to detect at the declared significance and power levels — determines required sample size: smaller MDE requires larger sample.

Incrementality testing

A measurement approach that holds out a randomly-selected group of eligible users from a lifecycle program and compares their behaviour to exposed users — reveals the true incremental impact of the program vs. organic baseline.

Holdout group

A randomly-selected group of eligible users held out of a program — they never receive the lifecycle communications. Comparing their outcomes to exposed users reveals the program's true causal impact.

False positive

An A/B test result declared significant when the apparent effect was actually due to chance — increases with each additional metric compared, with early peeking, and with multiple variants tested against a single control.

Power (statistical)

The probability that an A/B test correctly detects an effect when a real effect exists. 80% power is the operator standard — 80% of tests with real underlying effects will produce significant results.

Confidence interval

A range of values that, with a chosen level of certainty (usually 95%), contains the true effect size of an A/B test — a more informative metric than a single point estimate of lift.

Multi-armed bandit

An experimentation approach that dynamically shifts traffic toward the winning variant as results emerge — higher total conversion than traditional A/B tests when lift is real, but weaker statistical certainty about the final result.

Attribution window

The period after an email send during which subsequent conversions are credited to that send — typical windows are 24-72 hours for email, 30 days for display ads. Shorter windows under-credit the channel; longer windows over-credit.